1. Field of the Invention
The present invention relates to an improved blower for use in a variety of OA (office automation) appliances.
2. Description of the Related Art
Each OA appliance houses many electronic circuits within its housing, so that heat generated by electronic parts constituting those electronic circuits is hard to be discharged. Because of this, there is a fear that some of the electronic parts are broken or deteriorated. Particularly in view of a recent trend towards downsizing of the OA appliance, in which the appliance is simply reduced in size despite an absence of reduction in quantity of the generated heat so much, countermeasures against the heat have come to an important technical object. Then troubles that would be caused by heat generated inside are prevented by forming a ventilation hole on a side wall of the appliance and mounting a blower around the hole to discharge internal heat to the outside of the appliance.
An example of the blower that has been frequently used will now be described with reference to a half-sectional view in FIG. 5. Reference symbol 1 denotes a casing that is cylindrical and functions as a wind tunnel. A housing 2 is formed integrally with this casing 1 at the center. A bearing holder 3 is formed in the housing""s central portion. Outer races of bearings 4 and 5 are supported inside the bearing holder 3 and a shaft 6 is fitted and inserted to inner races of the bearings 4 and 5. A ring 7 is mounted at the lower end of the shaft 6 to thereby prevent the shaft 6 from being pulled out and to position the shaft 6 in the axial direction. A spring 8 is interposed between the bearings 4 and 5 in such a state where it is compressed to give the bearings 4 and 5 a force pulling them apart.
Reference symbol 9 denotes an impeller made of synthetic resins. This impeller 9 comprises a body 10 having in section a shape of letter L and blades 11 formed around the outer circumference of the body 10, which are integrally formed. When forming the impeller 9, a cup-shaped motor yoke 12 is placed inside the body 10, a zinc die-cast-made bush 13 attached to the shaft 6 is further put in the center of the motor yoke 12, and these are then integrated. The motor yoke 12 has a hole 12a with which a convex portion 10a of the body 10 is engaged. A ring-shaped magnet 14 is attached to the inner circumferential portion of the motor yoke 12. The shaft 6, the motor yoke 12, the impeller 9 and the magnet 14 together constitute a rotary part.
A stator core 16 around which a stator coil 15 is wound is arranged on the outside of the bearing holder 3 and the stator core 16 is fixed to the bearing holder 3 with adhesives to form a stationary part. A printed circuit board 17 on which electronic circuits composed of electric parts are installed as a brushless motor is mounted on a lower portion of the stator core 16. The electronic circuits incorporated into this printed circuit board 17 control electric current for rotating the rotary part relative to the stationary part. A pin-shaped connecting terminal 18 is projected downward from the stator core 16 to pierce through a part of the printed circuit board 17, thereby electrically connecting the stator coil 15 to the circuits on the printed circuit board 17.
The thus-constructed blower is used when mounted through the ventilation hole on the housing of the OA appliance. In the mounting work, the upper side of the blower in the drawing is directed to the outside of the housing of the OA appliance with the shaft 6 being directed in the horizontal direction. When a predetermined voltage is applied to a control circuit on the printed circuit board 17 under this state, the electric current controlled by the control circuit is caused to flow through the stator coil 15 so that the rotary part is rotated by a magnetic interference action between the magnetic flux generated in the stator core 16 and the magnetic flux generated by the magnet 14. The impeller 9 is rotated so that the air in the lower part of the housing in the drawing is sucked and is discharged toward the outside in the upper part in the drawing. With this air flow operation, the interior of the housing is cooled.
The blower formed as the above structure has no problem when used for cooling OA appliances. However, considering this structure from the view point of preservation of environment in the future, a portion where different kinds of materials are joined should be formed in such a manner that it can be easily disassembled upon disposal. The above-described structure does not meet this requirement because the bearing holder and the stator core are fixed to each other with adhesives, making disassembling work difficult.
The present invention has been made in view of the above, and an object of the present invention is therefore to provide a blower that is easy to be disassembled.
In order to attain the object above, according to a first aspect of the present invention, in a blower constructed by rotatably supporting a shaft with bearings arranged inside a bearing holder, rotatably fixing to the shaft a motor yoke, an impeller and a ring-shaped magnet to form a rotary part, arranging a stator core with a stator coil wound therearound in the inner circumferential portion of the magnet while providing a clearance which is supported by the outer circumferential portion of the bearing holder, it is characterized in that a setscrew for preventing the stator core from being pulled out is interposed between the bearing holder and the stator core. Incidentally, the xe2x80x9cblowerxe2x80x9d referred to herein means an axial flow fan motor and a centrifugal fan motor, and the centrifugal fan motor further includes a cross-flow type and motor impellized type.
Also, according to a second aspect of the present invention, the blower in the first aspect of the invention is characterized in that the head of the setscrew is slotted.
Furthermore, according to a third aspect of the invention, the blower in the first aspect of the invention is characterized in that a hexagonal hole is formed in the head of the setscrew.
Furthermore, according to a fourth aspect of the present invention, the blower in the first aspect of the invention is characterized in that the setscrew is formed from a tapping screw.
Furthermore, according to a fifth aspect of the present invention, the blower in the first aspect of the invention is characterized in that one sheet of the stator core has a thickness of 0.35 mm to 0.5 mm, and in that the pitch of the setscrew coincides with the thickness of the stator core per sheet.
With the structure according to each aspect of the present invention, the stator core can be readily separated from the bearing holder by turning the setscrew and loosening the engagement.